Compactor machines, also variously called compaction machines, are frequently employed for compacting fresh laid asphalt, dirt, gravel, and other compactable materials associated with road surfaces. For example, during construction of roadways, highways, parking lots and the like, loose asphalt is deposited and spread over the surface to be paved. One or more compactors, which may be self-propelling machines, travel over the surface whereby the weight of the compactor compresses the asphalt to a solidified mass. The rigid, compacted asphalt has the strength to accommodate significant vehicular traffic and, in addition, provides a smooth, contoured surface that may facilitate traffic flow and direct rain and other precipitation from the road surface. Compactors are also utilized to compact soil or recently laid concrete at construction sites and on landscaping projects to produce a densified, rigid foundation on which other structures may be built.
One such type of compaction machine is a drum-type compactor having one or more drums adapted to compact particular material over which the compactor is being driven. In order to compact the material, the drum-type compactor, or vibratory compactor, includes a drum assembly having a variable vibratory mechanism that, for example, includes inner and outer eccentric weights arranged on a rotatable shaft situated within a cavity of the inner eccentric weight. Both amplitude and frequency of vibration (also referred to as compaction effort) are typically controlled to establish the degree of compaction. Amplitude is often controlled by a transversely moveable linear actuator adapted to axially bear against an axially translatable key shaft, causing the key shaft to rotate. The rotation of the key shaft in turn alters relative positions of the inner and the outer eccentric weights to vary amplitude of vibration created within the drum. Frequency of vibration is controlled by changing the speed of a drive motor positioned within the compactor drum. Compaction effort is modified by either modifying the amplitude, frequency, or amplitude and frequency.
Typical vibratory compactors have either a single drum with a variable vibratory mechanism or two drums each having a variable vibratory mechanism. By way of example, U.S. Pat. No. 6,750,621 shows a vibratory compactor having two drums with variable vibratory mechanisms. Sensors not connected to the drums are used to collect certain vibratory characteristics about each drum and adjust the compaction effort of the drum to a selected setting. The control unit also calculates the difference between the measured vibratory characteristics on both the front and rear drums. The system disclosed by the '621 patent is a reactive system in which the compaction effort is continually adjusted based on the measured vibratory characteristics being different from the selected vibratory settings. The sensors are not measuring the compactability of the surface material and not proactively responding to the compactability of the surface material. As a result, it is possible to decompact or crush the surface material due to high compaction effort from the drum onto the surface material. The present disclosure is directed to one or more of the problems or issues set forth above.